1. Technical Field of the Invention
The present invention generally relates to Internet telephony (IP telephony). More particularly, the present invention is directed to a system and method for enabling local and global instant VoIP messaging over an IP network, such as the Internet, with PSTN support.
2. Description of the Prior Art
Traditional telephony is based on a public switched telephone network (i.e., “PSTN”). In the PSTN, a telephone terminal is electrically connected to a conventional or legacy switch. The telephone terminal and the legacy switch communicate via a proprietary protocol, which may be different depending on the vendor of the legacy switch. Circuit switching provides a communication path (i.e., dedicated circuit) for a telephone call from the telephone terminal to another device over the PSTN, including another telephone terminal. During the telephone call, voice communication takes place over that communication path.
An alternative to the PSTN is Voice over Internet Protocol (i.e., “VoIP”), also known as IP telephony or Internet telephony. In the IP telephony, a VoIP terminal device is connected to a packet-switched network (e.g., Internet) and voice communication from the VoIP terminal device is digitized, packetized and transmitted over the packet-switched network to a destination VoIP terminal device, which reconstructs the packets and audibly plays, stores or otherwise processes the transmission. The VoIP terminal device may be a VoIP telephone or a general-purpose personal computer (PC) enabled for IP telephony. More specifically, the PC is programmed with the software and equipped with audio input/output devices (e.g., a combination of microphone and speaker or a headset) to serve as a VoIP terminal device. The PC so enabled and equipped will herein be referred to as a VoIP terminal device or a VoIP softphone.
FIG. 1 is an illustrative example of a prior art IP telephony system 100. The IP telephony system 100 comprises a packet-switched IP network 102, such as the Internet, which transmits VoIP traffic from and to a plurality of terminal devices 104, 106 and 110. Terminal device 104 is a VoIP softphone that is enabled for IP telephony over the network 102. Terminal device 106 is a VoIP telephone, which is connected to the network 102 via a softswitch 108. The VoIP softswitch 108 is disposed on the packet-switched network (e.g., Internet) 102 between an origination terminal device (such as VoIP softphone 104) and a destination terminal device (such as VoIP telephone 106), and routes packets over the packet-switched IP network 102. The softswitch 108 may also manage and perform administrative functions for the terminal device or devices (e.g., VoIP telephone 106) to which it is connected. Whether the terminal device is a VoIP softphone 104 or a VoIP telephone 106, the terminal device is connected to the IP network 102 via a networking standard such as Ethernet, Bluetooth, IEEE 1394 (also known as “Firewire”), IEEE 802.11 (also known as “WiFi”), or networking over serial communication channels such as the Universal Serial Bus (i.e., “USB”). Data communication over the network then takes place using a connection protocol, e.g., transfer control protocol/Internet protocol (i.e., “TCP/IP”).
Further regarding FIG. 1, terminal device 110 is a legacy telephone that is connected to a legacy switch 112 for (circuit-switched) voice communications over the PSTN 116 with other terminal devices. A media gateway 114 may be provided between the legacy switch 112 and the packet-switched network 102 to enable IP telephony between the legacy telephone 110 and a VoIP terminal device, such as a VoIP softphone 104 or VoIP telephone 106. More specifically, the media gateway 114 converts the audio signal carried over PSTN to packets carried over the packet-switched IP network 102. In addition, a media gateway 118 may be disposed over the PSTN 116 and connected to a softswitch 120 to convert the audio signal from the legacy telephone 110 to packets routed over the IP network 102 via the softswitch 120.
Voice messaging in both the VoIP and PSTN is known. More specifically, the foregoing systems may be provided with a facility to allow users to leave voice messages for recipients, which is a feature that is familiar to anyone who uses a telephone. Conventionally, leaving a voice message involves dialing the recipient's telephone number (often without knowing whether the recipient will answer), waiting for the connection to be established, speaking to an operator or navigating through a menu of options, listening to a greeting message, and recording the message for later pickup by the recipient. In that message, the user must typically identify himself or herself in order for the recipient to return the call.
Instant text messaging is likewise known. More specifically, a user is provided with a client terminal, which is typically a general-purpose PC programmed with instant text messaging software and in data communication over an IP network with an instant text-messaging server. The instant text-messaging server presents the user, via the client terminal, with a list of persons who are currently “online” and ready to receive text messages on their own client terminals. The user then uses the client terminal to select one or more persons to whom the message will be sent and types in a text message. The text message is sent immediately via the text-messaging server to the selected one or more persons and is displayed on their respective client terminals.
However, notwithstanding the foregoing advances in the VoIP/PSTN voice communication and voice/text messaging, there is still a need in the art for providing a system and method for providing instant VoIP messaging over an IP network. More particularly, there is a need in the art for providing local and global instant voice messaging over VoIP with PSTN support.